I. Field of the Disclosure
The technology of the disclosure relates generally to removable memory cards.
II. Background
Mobile terminals have become ubiquitous in modern society. While mobile phones, and in particular, smart phones, have garnered a majority of the attention, numerous other mobile terminals such as cameras, audio players, video recorders, and the like are also widely available. Many of these devices rely on removable memory media to store data. For example, a camera may store photos on a removable memory card. Less portable computing devices, such as desktop computers, may also have receptacles that receive the removable memory card. In this regard, a person may take a picture with the camera, store the picture on the removable memory card, remove the card from the camera, insert the card into the receptacle on a desktop computer, and transfer the picture to a hard drive of the desktop computer.
Many removable memory cards are some form of Flash memory. However, even with the common Flash memory format, there are numerous proprietary removable memory cards, including those provided by Compact Flash (I and II), Secure Digital (SD) (SD, miniSD, microSD, SDHC, miniSDHC, microSDHC, SDXC), Memory Stick (Standard, Pro, Pro Duo, Pro-HG Duo, Micro (M2), xC), MultiMediaCard (MMC) (MMC, RS-MMC, MMCmobile, MMCplus, MMCmicro), Serial Peripheral Interface (SPI) mode of operation within a card format, xD (Standard, Type M, Type H, Type M+), XQD, or Ultra High Speed (UHS) (I and II).
In addition to the removable versions of Flash memory, a number of Flash memory protocols exist that are designed for embedded or otherwise non-removable memory units. Such embedded Flash memory units may be soldered or otherwise permanently affixed to printed circuit boards or substrates of an electronic device. One such protocol is the Universal Flash Storage (UFS) standard proposed by the Joint Electron Device Engineering Council (JEDEC).
To date, UFS has not been applied to a removable memory card protocol. Computing devices, or hosts, will need to be able to deal with UFS-compliant removable memory cards when such cards are available. To avoid addition of a dedicated UFS receptacle, hosts may need to support UFS-compliant cards via the same receptacle used to support SD-compliant cards. Such support will require hosts to be able to distinguish between UFS- and SD-compliant removable memory cards. One way for a host to distinguish between card types is by employing an additional pin in a receptacle that receives card type information from a switch that differentiates between UFS- and SD-compliant card form factors. However, employing an additional pin increases size and cost of the receptacle. Instead of employing an additional pin, a host may distinguish between UFS- and SD-compliant cards using protocol initialization signaling. For example, a host may employ a signaling sequence of first attempting to initialize a removable memory card using a SD protocol, and attempting to initialize the card using a UFS protocol only if the SD protocol initialization is unsuccessful. However, using a series of protocol initializations in this manner increases the amount of time required to initialize the removable memory card. Thus, it would be advantageous for hosts to be able to distinguish between UFS- and SD-compliant removable memory cards without requiring an additional pin or incurring increased card initialization time.